1. Field of the Invention
The present invention relates to a measuring instrument that detects a measured value as an electric signal and displays the measured value. More particularly, the present invention relates to a measuring instrument that detects the measured value and determines acceptance or rejection based on whether or not the measured value is within a preset tolerance range. Such a measuring instrument is applicable to a caliper gauge, a dial gauge and the like.
2. Description of Related Art
As such a dial gauge, there has been known an analog dial gauge in which a linear displacement of a spindle is converted into a rotational movement of an indicator through a movement conversion mechanism, an expansion mechanism or the like so as to read a measured value from a scale corresponding to the indicator, and a digital dial gauge in which an encoder is accommodated for detecting a liner displacement of a spindle as an electric signal so as to digitally display a measured value detected by the encoder.
The digital dial gauge is typically used when a high resolution, high accuracy and readability are required, which causes an economic burden, while the analog dial gauge is typically used when the high accuracy is not required. Also, the latter dial gauge is often used when acceptance or rejection is determined based on whether a measured value is within a predetermined range such as a tolerance.
However, in actual measurement, one of the dial gauges cannot be easily selected depending on an object to be measured, a measurement property, user's proficiency level or custom, and the like. Consequently, a dial gauge having both features of the digital dial gauge and the analog dial gauge has been required.
For example, in order to numerically check a deviation of a rejected measured value, the feature of the digital dial gauge needs to be added to the analog dial gauge used for determining acceptance when a measured value is within a tolerance range. Also, the feature of the analog dial gauge needs to be added to the digital dial gauge in order to roughly check a trend in a measured value without reading a digitally displayed value that instantly changes until a final value is determined.
Accordingly, there has been known a measuring instrument called as a digital and analog caliper gauge in which the two dial gauges are combined as disclosed in Document 1 (JP-A-06-288701).
The digital and analog caliper gauge includes a digital display for displaying measured data as a five-digit numerical value at a central position of a display surface of a slider, and an analog display for displaying the last two digits of the numerical value displayed on the digital display, the analog display surrounding the digital display. The analog display includes 100 display segments each having a predetermined width and length arranged at equal intervals on a circumference encircling the digital display, and displays the last two digits by controlling lighting of a single display segment corresponding to the measured value.
In the measuring instrument disclosed in Document 1, the measured value detected by the encoder is digitally displayed as a numerical value on the digital display, and the last two digits of the numerical value are displayed as a point on the analog display. Accordingly, three display segments are lighted at the same time. Namely, a display segment corresponding to the last two digits, a prior display segment thereto, and a subsequent display segment thereto are lighted at the same time.
Since the consecutive three display segments including the display segment corresponding to the last two digits of the measured value are lighted at the same time when the slider remains stationary, the lighted display segments can be visually checked easily.
However, the last two digits of the measured value instantly change when the slider moves. Accordingly, the display segments to be lighted on the analog display are changed at high speed and consequently blinking lights circularly move at high speed. At this time, the last two digits are not easily checked visually and considerable electric power consumption is required.